Leases - Additional Information (Detail) $ in Thousands		1 Months Ended								12 Months Ended
	Feb. 28, 2022 ft²	Jun. 30, 2022 ft²	Feb. 28, 2022 ft²	Jan. 31, 2022 ft²	Nov. 30, 2020	Apr. 30, 2019	Mar. 31, 2019	Jan. 31, 2016	Oct. 31, 2014	Dec. 31, 2022 USD ($) ft²	Dec. 31, 2021 USD ($)	Oct. 31, 2022 USD ($)
Lessee Lease Description [Line Items]
Operating lease right-of-use assets | $										$ 133,076	$ 79,143
Operating lease, liability | $										$ 130,703
Incremental borrowing rate										7.99%
Prepaid lease payments | $										$ 500
130 Brookline Street [Member]
Lessee Lease Description [Line Items]
Operating lease, description										In October 2014, the Company entered into an agreement to lease office and laboratory space at 130 Brookline Street in Cambridge, Massachusetts under an operating lease agreement with a term through January 2020. In April 2019, the lease was amended to extend the term for an additional five-year period, through January 2025.
Operating lease expiration									2020-01
Lessee operating lease extended expiration date						Jan. 31, 2025
Operating lease, options to extend										In April 2019, the lease was amended to extend the term for an additional five-year period, through January 2025
Operating lease, renewal term						5 years
Operating sublease, existence of option to extend							true
Operating lease, existence of option to terminate									true
130 Brookline Street [Member] | Second Amendment [Member]
Lessee Lease Description [Line Items]
Operating lease, description										In March 2020, the Company entered into a second amendment to this lease which extended the term by approximately six years through January 31, 2031.
Lessee operating lease extended expiration date										Jan. 31, 2031
Operating lease, existence of option to extend											true
Operating lease, options to extend										an option to extend the lease for two consecutive five-year terms
Operating lease, renewal term										6 years
40 Erie Street [Member]
Lessee Lease Description [Line Items]
Operating lease, description										In January 2016, the Company entered into a ten-year agreement to lease office and laboratory space at 40 Erie Street (the “40 Erie Lease”) in Cambridge, Massachusetts under an operating lease agreement, with an option to terminate the lease at the end of the sixth year and an option to extend the term of the lease for an additional three years.
Operating lease, existence of option to extend								true
Operating lease, options to extend										an option to extend the term of the lease for an additional three years
Operating lease, renewal term								3 years
Operating lease, term of contract								10 years
Operating lease, existence of option to terminate								true
Operating lease, option to terminate										option to terminate the lease at the end of the sixth year
Operating lease, terminate term								6 years
40 Erie Street [Member] | Second Amendment [Member]
Lessee Lease Description [Line Items]
Operating lease, description										In November 2020, the Company entered into a second amendment to the 40 Erie Lease which provides the Company with a right of first offer with respect to any space that becomes available at the 40 Erie Street building, and in consideration for this right the Company agreed to nullify the option to terminate the lease at the end of the sixth year that was included in the 40 Erie Lease
Operating lease, existence of option to extend					true
Operating lease, option to terminate										option to terminate the lease at the end of the sixth year
Operating lease, terminate term					6 years
Albany Lease [Member]
Lessee Lease Description [Line Items]
Area of space leased										39,000
Operating lease, description										In March 2020, the Company entered into an agreement to lease approximately 39,000 square feet of office and laboratory space at 281 Albany Street in Cambridge, Massachusetts under an operating lease agreement (the “281 Albany Lease”).
Term of lease										10 years
Operating lease, existence of option to extend											true
Operating lease, options to extend										The Company has the option to extend the 281 Albany Lease for two successive five-year terms
Tudor Lease Member
Lessee Lease Description [Line Items]
Area of space leased										13,662
Operating lease, description										In July 2021, the Company entered into an agreement to lease 13,662 square feet of office space at 17 Tudor Street in Cambridge, Massachusetts under an operating lease agreement (the “17 Tudor Lease”).
Term of lease										5 years
Operating lease, options to extend										The initial term of the 17 Tudor Lease is five years, and the Company has an option to extend the 17 Tudor Lease for one three-year term.
730 Main Lease [Member]
Lessee Lease Description [Line Items]
Percentage of Annual Increase										3.00%
Operating lease right-of-use assets | $												$ 36,400
Area of space leased										38,000
Operating lease, description										In January 2022, the Company entered into an agreement to lease approximately 38,000 square feet of office and laboratory space at 730 Main Street, Cambridge, Massachusetts under an operating lease agreement (the “730 Main Lease”). The initial term of the 730 Main Lease is
Term of lease				10 years
Base rent per square foot for first year				130.00
Operating lease, options to extend										the Company has the option to extend the 730 Main Lease for one five-year term.
Incremental borrowing rate												9.33%
840 Winter Street Lease [Member]
Lessee Lease Description [Line Items]
Percentage of Annual Increase										3.00%
Area of space leased	140,000
Operating lease, description										In February 2022, the Company entered into an agreement to lease approximately 140,000 square feet of office, general laboratory and manufacturing space located at 840 Winter Street, Waltham, Massachusetts (the “840 Winter Lease”), which will provide the Company with the ability to manufacture its own products in a good manufacturing practice (“GMP”) compliant facility as well as to supplement the Company’s current leased premises in Cambridge, Massachusetts. The 840 Winter Lease, including the obligation to pay rent, is expected to commence in 2024 for an
Term of lease	12 years		12 years
Base rent per square foot for first year			73.50
Operating lease, options to extend										The Company has the option to extend the 840 Winter Lease for two five-year terms.
640 Memorial Drive [member[
Lessee Lease Description [Line Items]
Percentage of Annual Increase										4.00%
Operating lease right-of-use assets | $										$ 30,700
Operating lease, liability | $										$ 30,200
Area of space leased		62,000
Operating lease, description										In June 2022, the Company entered into an agreement to lease approximately 62,000 square feet of office and laboratory space located at 640 Memorial Drive, Cambridge, Massachusetts under an operating lease agreement (the “640 Memorial Drive Lease”). The term of the lease is five years, ending in August 2027. The Company does not have an option to extend the 640 Memorial Drive Lease. The base rent under the 640 Memorial Drive Lease is approximately $97 per square foot per year during the first year of the term, which is subject to scheduled 4% annual increases, plus certain operating expenses and taxes. In September 2022 the Company determined, in accordance with ASC 842, that the commencement date for the lease had been met as the lessor had made the space available for the Company's use.
Term of lease		5 years
Base rent per square foot for first year		0.97
Operating lease, options to extend										The Company does not have an option to extend the 640 Memorial Drive Lease